Vacuum pump

ABSTRACT

A vacuum pump ( 10 ) has a vacuum-tight housing ( 12 ) and having a gas-tight electrical leadthrough assembly ( 20 ) for producing an electrical connection between an electrical component ( 14,16,18 ) within the housing ( 12 ) and the exterior of the housing. The leadthrough assembly ( 20 ) is formed by a housing opening ( 22 ), by a sealing compound body ( 24 ) seated on the opening, by an electric line in the sealing compound body ( 24 ), by a sealing ring ( 26 ) between the opening edge of the housing opening ( 22 ) and the sealing compound body ( 24 ), and by a fixing means ( 32 ) for fastening the sealing compound body ( 24 ) to the housing ( 12 ).

BACKGROUND

The invention relates to a vacuum pump wherein the pump housing isprovided with a gas-tight electrical leadthrough assembly.

Vacuum pumps normally comprise electrical components arranged within avacuum-tight housing, such as e.g. an electric drive motor, electricsensors, a magnetic bearing etc. The electrical components on the vacuumside have to be connected to the outer side of the housing throughelectric lines. For this purpose, electric lines have to be led from theinterior of the housing to the exterior of the housing via a gas-tightelectrical leadthrough assembly.

Known from the state of the art are leadthrough assemblies consisting ofa contact plate provided with contact pins passing therethrough, saidcontact plate being configured to close a corresponding opening of thehousing. With the aid of a sealing ring, the contact plate is sealedtowards the edge of said housing opening. The sealing of said contactpins in the contact plate can be effected only with difficulties andwill not be reliable in case that mechanical stresses happen to act onthe contact plate.

In view of the above, it is an object of the invention to provide avacuum pump whose housing is provided with a reliable gas-tightelectrical lead-through assembly.

SUMMARY

The vacuum pump according to the invention comprises a vacuum-tighthousing and an electrical component arranged within the housing. Thegas-tight electrical leadthrough assembly for producing an electricalconnection between said electrical component and the exterior of thehousing is formed by an opening in the housing; a sealing compound bodyseated on the opening of the housing, with an electric line, extendingbetween the inner side of the housing and the outer side of the housing,passing through said sealing compound body; a sealing ring arrangedbetween the opening edge of the opening of the housing and the sealingcompound body; and a fixing means for fastening the sealing compoundbody to the housing. Thus, the leadthrough assembly substantiallyconsists of three parts, namely the sealing compound body having all ofthe electric lines cast into it, the sealing ring for safeguarding agas-tight and vacuum-tight sealing action between the sealing compoundbody and the edge of the opening, and a sealing-compound body fixingmeans which is effective to permanently press the sealing compound bodyonto the opening edge of the opening of the housing.

The sealing compound has a certain elasticity, safeguarding thegas-tight and vacuum-tight passage of the electric line or lines throughthe sealing compound body. Preferably, both proximally and distally, theelectric line or lines should at least slightly project outwards from ofthe sealing compound body so as to allow for the attachment of electricconnection lines. The sealing effect between the sealing compound bodyand the edge of the opening is reliably obtained by a sealing ring.

The thickness of the sealing compound body should be at least 5 mm andpreferably 10 mm so as to guarantee a sufficiently long sealing spacebetween the electric line and the sealing compound.

By casting all of the electric lines into a monolithic, elastic sealingcompound body, it is made possible to realize a reliable, vacuum-tightpassage in a relatively simple manner also in case of a large number ofelectric lines. This is of relevance particularly for vacuum pumps withmagnetic bearings since these pumps will often require a number of 50 ormore electric conduits to be led through the vacuum-tight housing.

According to a preferred embodiment, the sealing compound body is seatedfrom the outside onto the opening edge of the opening of the housing.During operation, under the effect of the differential pressure betweenthe atmospheric air pressure acting from the outside and the vacuumprevailing in the housing, the sealing compound body will be pressedonto the edge of the opening of the housing. In this manner, the sealingeffect between the sealing compound body and the edge of the opening ofthe housing will be additionally intensified when the vacuum pump isoperated.

Preferably, the fixing means is a sealing-compound housing configured toalmost fully take up the sealing compound and to press the sealingcompound against the edge of the opening of the housing. Thesealing-compound housing comprises only one proximal opening and onedistal opening for the electric line or lines. The primary function ofthe sealing-compound housing resides in fixing the sealing compound bodyin place while, on the other hand, this housing does not primarily havea sealing function. Nonetheless, the sealing-compound housing may infact have a sealing effect as well.

According to a preferred embodiment, the electric line can comprise aconductive board arranged in the sealing compound. Thus, the electricline is partially realized in the form of a conductor trace on a printedcircuit board. The electric line can further comprise respectively oneplug projecting from the sealing compound body towards the interior ofthe housing, and one plug projecting from the sealing compound bodytowards the exterior of the housing. Said two electric plugs can beconnected to each other by the printed circuit board but can also beelectrically connected to each other in another manner.

According to a preferred embodiment, the printed circuit board compriseselectronic components. Possible electronic components in this regard areall electronic components which may serve for amplification,interference suppression or another manipulation of electric signals,i.e. components such as, for instance, amplifiers, suppressor chokes andcapacitors, integrated circuits for signal processing, etc.

Preferably, the electronic component is a readable pump-data memoryadapted for storage therein of pump-specific functional parameters, e.g.an error history of the respective vacuum pump, and for retrievaltherefrom of such functional parameters at any time.

Preferably, the sealing compound material is an epoxy resin. Epoxyresins are vacuum-tight and elastic and are castable at relatively lowtemperatures which are not destructive to electronic components.

The following is a detailed description of an embodiment of theinvention with reference to the drawing.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE schematically shows a vacuum pump and, in partly sectionalview, the vacuum pump housing provided with a gas-tight electricallead-through assembly.

DETAILED DESCRIPTION

Schematically shown in the FIGURE is a vacuum pump 10 which can beconfigured as a displacement pump but preferably will be configured as ahigh-vacuum turbomolecular pump with magnetic bearing.

Vacuum pump 10 comprises a vacuum-tight metal housing 12 having ahousing wall 13 and accommodating a plurality of electrical components14,16,18, notably an electric drive motor 14, a magnetic bearing 16 aswell as pump sensors 18. Drive motor 14 is operative to drive a pumprotor of the turbomolecular pump via a shaft 17.

Vacuum pump 10 is provided with a gas-tight electrical leadthroughassembly 20 for establishing an electrical connection between saidelectrical components 14,16,18 and the exterior of said housing.Leadthrough assembly 20 is substantially formed by a housing opening 22in housing wall 13; a sealing compound body 24 seated on said housingopening 22 on the outside of the latter; an elastic sealing ring 26between an opening edge 28 of housing opening 22 and the sealingcompound body; a fixing means 32 formed as a sealing-compound housing30; and an electric line 34. Said sealing ring 26 is seated in anannular groove 27 of sealing compound body 24.

Electric line 34 is formed by a proximal electric plug 40, a distalelectric plug 42, and a printed circuit board 44 comprising conductivetraces and electrical components 46,47,48. Said electrical components46-48 are an integrated circuit 46 and passive components 47,48. Saidplugs 40,42 comprise more than 50 plug pins, each one of themindividually connected to conductive traces on circuit board 44.

Stored in integrated circuit 46 are functional parameters and data ofvacuum pump 10. The functional parameters are pump-specific and includean error history of vacuum pump 10 which, using a suitable readingdevice 50, can be read out via distal plug 42 through an electrical dataline 52 adapted to be plugged onto plug 42.

All parts of electric line 34 are enclosed in a gas-tight manner withinthe sealing compound body 24 cast therearound. The sealing compoundmaterial is an epoxy resin. The epoxy resin can be provided withfine-granulated admixtures which have a positive influence on thermalexpansion, thermal conductivity and/or other physical parameters.

Under the effect of the cup-shaped sealing-compound housing 30 forming afixing means 32 and being fixed, e.g. screwed, to the outside of housing30, the sealing compound body 24 is pressed onto said opening edge 28,resulting in a gas-tight and vacuum-tight sealing condition betweenopening edge 28 and sealing compound body 24.

The invention has been described with reference to the preferredembodiments. Modifications and alterations may occur to others uponreading and understanding the preceding detailed description. It isintended that the invention be construed as including all suchmodifications and alterations insofar as they come within the scope ofthe appended claims or the equivalents thereof.

1. A vacuum pump comprising a vacuum-tight housing, an elastic componentarranged within said housing, a gas-tight electrical leadthroughassembly for producing an electrical connection between an electricalcomponent within the housing and the exterior of the housing, whereinsaid leadthrough assembly is formed by a housing opening, a sealingcompound body positioned on said housing opening and enclosing anelectric line extending between the interior of the housing and theexterior of the housing, a sealing ring between an opening edge of thehousing opening and the sealing compound body, and a fixing means forattachment of the sealing compound body to the housing.
 2. The vacuumpump according to claim 1, wherein said sealing compound body is mountedto said housing opening from the outside.
 3. The vacuum pump accordingto claim 1, wherein said fixing means is a sealing-compound housing. 4.The vacuum pump according to claim 1, wherein said electric linecomprises a circuit board arranged within the sealing compound body. 5.The vacuum pump according to claim 1, wherein said electric linecomprises respectively one electric plug towards the interior andtowards the exterior.
 6. The vacuum pump according to claim 4, whereinsaid circuit board comprises electronic components.
 7. The vacuum pumpaccording to claim 6, wherein one of said electronic components isconfigured as a readable pump-data memory.
 8. The vacuum pump accordingto claim 1, wherein the material of the sealing compound body is anepoxy resin.